Adjusted incidence rate ratios with 95% CI for seropositive* and seronegative† rheumatoid arthritis by cumulated styrene exposure level in 59 997 male and 12 215 female workers in the Danish reinforced plastics industry, 1979 to 2012
| Styrene exposure level | Rate ratio‡ seropositive | Rate ratio‡ seronegative | ||||||
| n | Men | n | Women | n | Men | n | Women | |
| 156 | 60 | 157 | 84 | |||||
| ≤17 mg/m3 years | 1 | 1 | 1 | 1 | ||||
| 18–67 mg/m3-years | 1.19 (0.79 to 1.81) | 0.89 (0.45 to 1.76) | 1.17 (0.75 to 1.83) | 0.97 (0.59 to 1.58) | ||||
| ≥68 mg/m3‡-years | 1.11 (0.73 to 1.70) | 1.95 (1.05 to 6.61) | 1.52 (0.99 to 2.34) | 0.49 (0.24 to 0.98) | ||||
| Per 100 mg/m3-years | 0.98 (0.93 to 1.04) | 1.11 (1.01 to 1.22) | 1.04 (1.02 to 1.07) | 0.87 (0.70 to 1.09) | ||||
*Seropositive cases: ICD-10 codes: M050, M051, M051A-F, M052, M053, M058, M059.
†Seronegative cases: ICD-10 codes: M060, M068, M069.
‡Adjusted for age, calendar year of follow-up and educational level.
ICD-10, International Classification of Diseases, 10th version.